As operating mechanisms to operate a gas circuit breaker, the followings are available: a spring operating mechanism adapted to obtain operating power by releasing the spring force held by an urged operating spring; and a pneumatic operating mechanism or a hydraulic operating mechanism adapted to obtain operating power through the use of pneumatic pressure or hydraulic pressure. However, as for operation by spring force, there are several difficulties in improving operational reliability: for instance, elastic force of a spring is not always constant; the accuracy of positioning a spring is low; and such a mechanism is complex and composed of many parts.
In regard to an operating method using pneumatic pressure or hydraulic pressure, there is a possibility that a working fluid may leak with a certain degree of change in ambient temperature and there is also a possibility that the malfunction or failure of any one of the components, if occurs, may result in failure of operation of the entire mechanism. In addition, in each of the above-mentioned operating mechanisms, its operating energy is determined in advance by the spring force held by the urged spring, hydraulic pressure, etc. and it is unable to make an operating characteristic change adaptively for each action of current interruption or during an action.
Instead of the above-mentioned operating methods which have so far been used, a technique has recently emerged for producing operating power by electricity or magnetic force, which is described in, e.g., Patent Document 1 and Patent Document 2.
In Patent Document 1, it is described that an actuation means that supplies energy for performing an open/close switching action transfers an electrical signal for driving a motor to the motor in order to achieve an electrical signal to drive an electric motor so that a position control motor operatively coupled to a movable contact and the movable contact achieve predetermined movement regularity.
In Patent Document 2, there is provided an actuator including a coil that is provided so as to be linearly movable in an axial direction between an inner permanent magnet and an outer permanent magnet and a nonmagnetic movable element, on one end of which the coil is placed, and which, when current is supplied to the coil, linearly moves in an axial direction between the inner and outer permanent magnets by repulsion electromagnetic force produced by a magnetic field generated by the inner and outer permanent magnets and a current density of the coil and there is described a circuit breaker including an insulating operating rod that is coupled to the other end of the movable element and performs a closing action and an opening action by its linear movement made by the movable element.